Cutting-edge engineering gives Sea to Summit® eVent® Compression Dry Sack a clear advantage over traditional dry bags. Using a unique combination of a 70-denier polyurethane-coated-nylon body and lid, and 40-denier nylon-face eVent waterproof/breathable laminate, these waterproof bags let you push the air out without the need for a purge valve. That also ensures even pressure distribution, unlike ordinary dry bags that can balloon or pop open from uneven pressure. 4 compression straps ensure a minimal footprint, while the Hypalon roll-top non-wicking closure provides a secure seal. Manufacturer's lifetime limited warranty.